Class 1 Circuit Defintion

[KiloMike21]

My question is, is a typical branch circuit (e.g. 20A 120V circuit feeding outlets) a Class 1 Circuit? What is the code section that describes this?

In NEC 2017 art 725 defines a class 1 circuit as the 'portion of the wiring system between the load side of the overcurrent or power-limited supply and the connected equipment'. Within the scope of this article in 2017 this would only apply to remote control, signaling, and power limited circuits.

In NEC 2020 the aforementioned definition is moved to Art 100 which would imply to me that it applies to all branch circuits, but the informational note provided points at 725.41 for voltage and power limitations of class 1 circuits. 725.41 delineates Class 1 circuits into power-limited, and remote control and signaling circuits.

I am being told that a branch circuit is a class 1 circuit and it has always been that way but I cannot seem to find this within the code.

Thanks

 

[infinity]

The 2020 breaks it down into Class 1 power-limited circuits and Class 1 remote-control and signaling circuits so the circuit is either one of those. That does not apply to all branch circuits.

 

[don_resqcapt19]

CMP 3 indicates in a panel statement that non-power limited Class 1 remote control and signaling circuits are really branch circuits, but all branch circuits are not Class 1 circuits.

 

[hbiss]

Within the scope of this article in 2017 this would only apply to remote control, signaling, and power limited circuits.

The 2020 breaks it down into Class 1 power-limited circuits and Class 1 remote-control and signaling circuits so the circuit is either one of those.

That's the way I always understood it.

CMP 3 indicates in a panel statement that non-power limited Class 1 remote control and signaling circuits are really branch circuits, but all branch circuits are not Class 1 circuits.

They certainly cleared that up.

-Hal

 

[victor.cherkashi]

My question is, is a typical branch circuit (e.g. 20A 120V circuit feeding outlets) a Class 1 Circuit? What is the code section that describes this?

In NEC 2017 art 725 defines a class 1 circuit as the 'portion of the wiring system between the load side of the overcurrent or power-limited supply and the connected equipment'. Within the scope of this article in 2017 this would only apply to remote control, signaling, and power limited circuits.

In NEC 2020 the aforementioned definition is moved to Art 100 which would imply to me that it applies to all branch circuits, but the informational note provided points at 725.41 for voltage and power limitations of class 1 circuits. 725.41 delineates Class 1 circuits into power-limited, and remote control and signaling circuits.

I am being told that a branch circuit is a class 1 circuit and it has always been that way but I cannot seem to find this within the code.

Thanks

“Typical branch circuit (e.g. 20A 120V circuit feeding outlets)” is powered from building wiring system. In this case there is no limit mentioned in 725.41 (A).
Reference: NEC-2017-725.41 (A) Class 1 Power-Limited Circuits. These circuits shall be supplied from a source that has a rated output of not more than 30 volts and 1000 volt-amperes.

 

[victor.cherkashi]

I recently run into similar situation when and had hard time to decide if the 1KVA (120V to 24V) transformer supplying a turnstile in building lobby can be classified as “Class 1 power supply”. I was not sure if the 24V wiring of the transformer powering the turnstile is “Remote-Control and Signaling Circuits”.

Conductor to an electrode system from transformer is not required if the situation described above is class 1 wiring.
Reference: NEC-2017 250.30(A)(5) Exception No. 3 says a grounding electrode conductor shall not be required for a system that supplies a Class 1, Class 2, or Class 3 circuit and is derived from a transformer rated not more than 1000 volt-amperes, provided the grounded conductor is bonded to the transformer frame or enclosure by a jumper sized in accordance with 250.30(A)(1)…